Data transmission of high-speed data at rates having bit periods on the order of one nanosecond over distances on the order of one meter requires relatively high performance interfaces, yet also requires or benefits from limited and controlled rise and fall times to minimize distortion, signal reflections, and electromagnetic interference (EMI). The root causes of distortion and reflection include skin effects in conductors, the high-frequency loss behavior of circuit board dielectric materials, and various physical discontinuities at bends, vias, and connectors. Several high speed interface standards have seen little use and success because the short rise and fall times used to limit delays and signal degradation under slow conditions (such as worst-case devices, low voltage, and high temperature) also produce excessive slew rate which leads to signal reflections and EMI, under conditions which give faster device operation. Providing the needed tight control of rise time usually introduces drive circuitry complications and requires ultimate speed capability much greater than the controlled rate. Such added complexity usually significantly increases signal propagation time through such driver circuitry. When factors such as supply voltage, temperature, and device manufacturing tolerances are taken into account, it is common for circuits to have a two-to-one practical range or even wider ranges in speed performance. Such wide ranges require either system designs predicted on the lowest-performance circuits or selection of the higher-performance circuits, with consequent waste of the lower-performance circuits.